Perhaps the most significant reunion that occurs at the parlay is the one between The Hound and The Mountain. When he sees his zombie brother enter the pit, The Hound walks straight up to him and reminds him that they still have a score to settle. It's hard to know exactly how much The Mountain understands in his current state, but it's clear the show is setting up a showdown between the brothers thanks to The Hound's words.
He tells his big brother, "You're even uglier than I am now. What did they do to you? Doesn't matter, it's not how it ends for you, brother. You know who's coming for you. You've always known." Cleganebowl 2019? We can only hope.